CGM's (Continuous glucose monitors)

I have had the chance to get two continuous glucose monitors covered by my insurance and have been using them for about 14 months. However, I have found that they are not all they are cracked up to be. They have what is known as a "lag time" and they are about 15-20 minutes behind what your glucose actually is. So when it finally beeps you to tell you your blood glucose is going low, you've already realized it through shaking or someone alerting you or knowing yourself that something is wrong. Also, when it beeps you to tell you that you're hihg, you give insulin to correct. It takes it forever to reflect this on the CGM, so you may give more insulin than what is really needed. I am so disappointed in the technology not being better with this. Please give me your thoughts and share any experiences you have had with this. Thanks. Reflib